NEW YORK (CBSNewYork) — Mayor Bill de Blasio and police Commissioner Bill Bratton are promising a full and thorough investigation into the death of a Staten Island man while in police custody.

Two police officers — an eight-year veteran and a four-year veteran — have been placed on administrative duty after the death of Eric Garner, 43, CBS 2’s Marcia Kramer reported. Garner went into cardiac arrest Thursday while being placed under arrest, police said.

The two cops have been allowed to keep their guns while the investigation continues.

De Blasio Offers Condolences To Family Of Man Who Died During Arrest

De Blasio offered his condolences to Garner’s family Friday.

“This is a terrible tragedy that occurred yesterday, a terrible tragedy that no family should have to experience,” de Blasio told reporters.

“Like so many New Yorkers, I was very troubled by the video I reviewed earlier today,” the mayor added.

Garner, an asthmatic who weighed at least 350 pounds, was placed in a choke hold by one cop. The father of six had a record of 31 previous arrests for charges that included possession of controlled substances and illegal cigarettes, CBS 2’s Lou Young reported.

“Choke holds are in fact prohibited by the New York City Police Department because of the concerns of potential death arising from them,” Bratton said.

The case is being investigated by the NYPD’s internal affairs unit, the medical examiner’s office and the Staten Island district attorney.

De Blasio Promises Full Investigation Into Death Of S.I. Man While In Police Custody

The encounter was captured on cellphone video. It shows police approaching the man for allegedly selling illegal untaxed cigarettes.

Garner is heard in the video telling police to leave him alone. An officer behind Garner then seizes him around the neck and takes him to the ground, the video shows.

“I can’t breathe. I can’t breathe,” Garner is heard saying.

A short time later, Garner appears to be unconscious, the video shows.

He was taken to Richmond University Medical Center, where he was pronounced dead, according to police.

“And just leave him on the ground and not even try to save his life,” one woman told WCBS 880’s Peter Haskell. “He didn’t deserve that.”

“They put him in a headlock, and they put him to sleep and that’s it,” one man told 1010 WINS’ Carol D’Auria. “He’s out cold. They killed him. They choked him to death. That’s it. Choke hold.”

Friends Of SI Man Who Died During Arrest Frustrated With Police

“He didn’t resist at all,” a man who goes by the name “Pop” told Haskell. “I saw the thing from the beginning to the end. He did not resist.”

The incident is causing considerable community outrage.

As CBS 2’s John Slattery reported, Garner’s wife, Esaw, was with her youngest child as friends and supporters protested the man’s death Friday. She, however, was too distraught to speak.

Supporters told D’Auria they are frustrated and angry because officers are always singling out and harassing black men.

The group Communities United for Police Reform issued a statement saying: “It’s yet another example of unnecessary police encounters resulting from broken window-style policing that targets New Yorkers of color, in this case escalating with fatal consequences.”

Though many who knew Garner said the mayor’s reaction was appreciated, Young reported.

“It gives us a little relief that they’re going to investigate and do something about this,” said witness Taisha Allen.

“They’re going to investigate, and that’s good,” said Jeanette Wilson, a friend of Garner’s.

The NYPD’s union asked New Yorkers to reserve judgment until an investigation is completed.

“Not wanting to be arrested does not grant an individual the right to resist arrest nor does it free the officers of the obligation to make the arrest,” Patrolmen’s Benevolent Association President Patrick J. Lynch said in a statement. “In these cases, justice for all involved demands a complete and thorough investigation of all the facts before any conclusions are drawn.”

Commissioner Bratton said he might order re-training as a result of Garner’s death, Young reported.

“Policing is all about constantly trying to prevent and learn when something does happen,” the commissioner said.

The mayor tried to keep a lid on community unrest as he is about to leave for a family vacation to Italy. The mayor was scheduled to leave Friday night but has pushed his departure back to Saturday to tend to city business, his spokesman said Friday afternoon.

“I assure all New Yorkers there will be a full and thorough investigation,” de Blasio said.

The Rev. Al Sharpton has already taken up the case. He scheduled a news conference for Saturday morning with Garner’s family and community leaders, Kramer reported.